a nice arvata

Cho A₌\(\dfrac{3n-5}{n+4}\) tìm n ϵ Z để A có giá trị nguyên

Vì a,b=1

nên:

_ a+b=1+1=2

_ a-b=1-1=0

có gì đâu?

Câu a: 800 con

Choose the correct tense of verb

1. Listen! I _________________ (think) someone _________________ (knock) at the door.

2. We __________________ (not/know) why Sarah is upset, but she __________________ (not/speak) to us for ages.

3. The Earth _________________ (circle) the Sun once every 365 days.

4. Why _____________________ (you/stare) at me? I suppose you _______________ (not/see) a woman on a motorbike before!

5. How many times _________________ (you/see) him since he went to London?

6. Trevor and Laura like Scabble. They _________________ (play) it most evenings.

7. The number of vehicles on the road ______________ (increase).

8. “Sorry I’m late.” “That’s all right. I _____________________ (not/wait) long.”

9. Mrs. Green always _______________ (go) to work by car, but this week she ____________________ (travel) by bus.

10. We _______________ (be) from French. We ___________________ (be) there for 20 years.

11. He ______________ (work) as a teacher five years ago.

12. Lana _______________ (see) a movie at Great Show theater tonight.

13. Hoang _______________ (call) you many times last night.

14. Linh’s grandfather ______________ (die) 30 years ago.

15. My mother ________________________ (be/water) her cactus trees on the balcony.